=[(4x+5)/(x+1)(x-1)-3(x+1)/(x+1)(x-1)]÷(x+2)/(x+1)(x-1)
=[(4x+5)-3(x+1)]/(x+1)(x-1) ×(x+1)(x-1)/(x+2)
=(x+2)/(x+2)
=1
当x=3时 原式=1